Similar to circle sphere is a two dimensional space where the set of points that are at the same distance r from a given point in a three dimensional space. In analytical geometry with a center and radius is the locus of all points is called sphere.

Circumference:

The distance around a circle is called its circumference.The circumference of the circle is \(\displaystyle{C}={2}\pi{r}\)

Taking \(\displaystyle\pi\stackrel{\sim}{=}\frac{{22}}{{7}}\)

The object is to find the circumference for the given circle as follows. The radius of the circle is r=21

Then the circumference of the circle is,

\(\displaystyle{C}={2}\pi{r}\)

\(\displaystyle{C}={2}{\left(\frac{{22}}{{7}}\right)}{\left({21}\right)}\)

C=132 cm.

So the circumference of the circle is approximately 132 cm.

Circumference:

The distance around a circle is called its circumference.The circumference of the circle is \(\displaystyle{C}={2}\pi{r}\)

Taking \(\displaystyle\pi\stackrel{\sim}{=}\frac{{22}}{{7}}\)

The object is to find the circumference for the given circle as follows. The radius of the circle is r=21

Then the circumference of the circle is,

\(\displaystyle{C}={2}\pi{r}\)

\(\displaystyle{C}={2}{\left(\frac{{22}}{{7}}\right)}{\left({21}\right)}\)

C=132 cm.

So the circumference of the circle is approximately 132 cm.